IXFLUEtfCE OF HOT WOEKIKG- ON STEEL, 273
this will tend to lessen the ductility rather than make up for the reduction caused by the larger section. In plates below three-eighths inch in thickness it is also necessary to make allowances, since it is almost impossible to finish them at a high temperature, and the test will give a high ultimate strength and a low ductility.
These conditions have now been officially recognized by the United States Government, for the rules of the Board of Supervising Inspectors, issued January, 1899, contain the following clause:
"The sample must show, when tested, an elongation of at least 25 per cent, in a length of two inches for thicknesses up to one-quarter inch, inclusive; and in a length of four inches, for over one-quarter to seven-sixteenths, inclusive; and in a length of six inches,, for all thicknesses over seven-sixteenths inch and -under 1% inches."
It is to be hoped that constructive engineers will follow this example in recognizing the influence of causes over which the manufacturer has no control.